From: Saso Kiselkov Date: Thu, 22 May 2014 09:11:57 +0000 (+0100) Subject: Illumos 4897 - Space accounting mismatch in L2ARC/zpool X-Git-Tag: zfs-0.6.4~211 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3bec585e6c86de869ba1bf132567ed2a01d6a15b;p=zfs Illumos 4897 - Space accounting mismatch in L2ARC/zpool 4897 Space accounting mismatch in L2ARC/zpool Reviewed by: Matthew Ahrens Reviewed by: Boris Protopopov Approved by: Dan McDonald From the illumos issue tracker: L2ARC vdev space usage statistics are calculated as the delta between the maximum and minimum vdev offset ever written to by the L2ARC fill thread, but do not inform the user of how much space in between these two offsets is actually taken up by cached buffers. This fix changes that so that vdev space usage stats on L2ARC devices accurately track the volume of buffers stored on them, allowing users to see the exact L2ARC usage in "zpool iostat -v". References: https://www.illumos.org/issues/4897 https://github.com/illumos/illumos-gate/commit/3038a2b Ported by: Tim Chase Signed-off-by: Brian Behlendorf Closes #2555 --- diff --git a/module/zfs/arc.c b/module/zfs/arc.c index ec006cb0f..ad29237b9 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -22,7 +22,7 @@ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2013 by Delphix. All rights reserved. * Copyright (c) 2013 by Saso Kiselkov. All rights reserved. - * Copyright 2013 Nexenta Systems, Inc. All rights reserved. + * Copyright 2014 Nexenta Systems, Inc. All rights reserved. */ /* @@ -1701,6 +1701,8 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr) list_remove(l2hdr->b_dev->l2ad_buflist, hdr); ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size); ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize); + vdev_space_update(l2hdr->b_dev->l2ad_vdev, + -l2hdr->b_asize, 0, 0); kmem_cache_free(l2arc_hdr_cache, l2hdr); arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS); if (hdr->b_state == arc_l2c_only) @@ -3791,6 +3793,8 @@ arc_release(arc_buf_t *buf, void *tag) if (l2hdr) { ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize); + vdev_space_update(l2hdr->b_dev->l2ad_vdev, + -l2hdr->b_asize, 0, 0); kmem_cache_free(l2arc_hdr_cache, l2hdr); arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS); ARCSTAT_INCR(arcstat_l2_size, -buf_size); @@ -4637,6 +4641,7 @@ l2arc_write_done(zio_t *zio) arc_buf_hdr_t *head, *ab, *ab_prev; l2arc_buf_hdr_t *abl2; kmutex_t *hash_lock; + int64_t bytes_dropped = 0; cb = zio->io_private; ASSERT(cb != NULL); @@ -4684,6 +4689,7 @@ l2arc_write_done(zio_t *zio) */ list_remove(buflist, ab); ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize); + bytes_dropped += abl2->b_asize; ab->b_l2hdr = NULL; kmem_cache_free(l2arc_hdr_cache, abl2); arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS); @@ -4703,6 +4709,8 @@ l2arc_write_done(zio_t *zio) kmem_cache_free(hdr_cache, head); mutex_exit(&l2arc_buflist_mtx); + vdev_space_update(dev->l2ad_vdev, -bytes_dropped, 0, 0); + l2arc_do_free_on_write(); kmem_free(cb, sizeof (l2arc_write_callback_t)); @@ -4841,6 +4849,7 @@ l2arc_evict(l2arc_dev_t *dev, uint64_t distance, boolean_t all) arc_buf_hdr_t *ab, *ab_prev; kmutex_t *hash_lock; uint64_t taddr; + int64_t bytes_evicted = 0; buflist = dev->l2ad_buflist; @@ -4939,6 +4948,7 @@ top: if (ab->b_l2hdr != NULL) { abl2 = ab->b_l2hdr; ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize); + bytes_evicted += abl2->b_asize; ab->b_l2hdr = NULL; kmem_cache_free(l2arc_hdr_cache, abl2); arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS); @@ -4956,7 +4966,7 @@ top: } mutex_exit(&l2arc_buflist_mtx); - vdev_space_update(dev->l2ad_vdev, -(taddr - dev->l2ad_evict), 0, 0); + vdev_space_update(dev->l2ad_vdev, -bytes_evicted, 0, 0); dev->l2ad_evict = taddr; } @@ -5204,15 +5214,13 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, ARCSTAT_INCR(arcstat_l2_write_bytes, write_asize); ARCSTAT_INCR(arcstat_l2_size, write_sz); ARCSTAT_INCR(arcstat_l2_asize, write_asize); - vdev_space_update(dev->l2ad_vdev, write_psize, 0, 0); + vdev_space_update(dev->l2ad_vdev, write_asize, 0, 0); /* * Bump device hand to the device start if it is approaching the end. * l2arc_evict() will already have evicted ahead for this case. */ if (dev->l2ad_hand >= (dev->l2ad_end - target_sz)) { - vdev_space_update(dev->l2ad_vdev, - dev->l2ad_end - dev->l2ad_hand, 0, 0); dev->l2ad_hand = dev->l2ad_start; dev->l2ad_evict = dev->l2ad_start; dev->l2ad_first = B_FALSE;